Air-current indicator for aeroplanes



L. B. SPERRY. MR CURRENT INDICATOR FOR AEBOPLANES- APPLICATION FILED OCT. 9.. IBIS- latented July 19, 1921.

filull'llu l RED Inn Enron LAWRENCE B. SPERRK I by g 7 UNITED STATES B. SPEZBBY, 01' BROOKLYN, NEW YQB-K, ASSIGNOR THE SPEBRY GY BO- SCOPE COHBAHY, E BROQKLYN, NEW YQBK, A GQBPORATION 0 3 NEW YOBK.

PATENT OFFICE.

' AIR-CURRENT IIPTDICATOR FOB AEBOPLA'NES:

- To allwhom it may concem:

Be it known that I, Lawnnnon B. SPERRY,

. a. citizen. of the United States, residing at 1505 Albemarle road, Brookl n, in the county of Kings andState of New ork,have invented certain'new and useful Improvements in Air-Current Indicators for Aeroplanes, of which the following is a specifie cation.

This invention relates to indicators for air craft, and more especially to the typeof in:

-"dicator which shows the direction of flight through the air, either inazimuth-or 'in elevation, or both. 7

The object of my invention is to improveupon indicators of this character, which may be termed air current indicators, so that the pilot will be kept informed at all times of the conditions of flight of the machine.

" For this purpose I- prefer to provide both means for showing the direction of flight in elevation or an angle of incidence indicator, and means for showin the direction of flight in azimuth or a side s p indicator. Both of these indicators are based upon the relative directions of theair currents and the aeroplane. A further ob'ect of the invention is to so construct the in 'cator as to be visible from the pilots seat irrespective of the position of the propeller. This has especial application in a tractor machine in which the propeller will obscure the view of the usuai types of indicators.

Referrin to the drawings in which, what I now "consider to be the rferredjorm of my invention is shown, Figure 1 1s alongitudinal section partly in plan of the actusting portion of the indicator. Fig. 2 is a 18118. -Fig. 7 s a view of the receiver. Fig. .is a detail on an enlarged scale taken on line8-8of Fig. 3. r

The actuating orsending instrument may be secured in a convenient 'tion on the. aeroplane and is represents in Fi 1 .as'

clamped to a strut 1 by means of 0 amp 2. The casing 3 which sup orts the mechanism is pivoted oii clamp 2 y means of a bolt and 20 adjustably positioned the cas- Specification ofLctters recent. PatentedJuly 19,1921,

Application filed. October a, me. Serial no. 124,448.

4. Ad ustmentof the casing on the clamp may be secured by means of a pair of 'set screws 5 and 5, which bear on opposite sides of a lug 7 extending rearwardly from casing 3. By oosening one of said screws and tightsuing the other the position of the casing with respect to the an he of incidence of the air craft maybe readi y adjusted so that the contacts hereinafter described may be posit oned in their proper location. '65

Rotatably mounted within the casing is a shaft 6 to which is secured one or more contact arms 7 and 8. The ends 9 and 10 of the two arms are out of alinement as shown in F 1. The end 10 of arm 8 is adapted to'70 Stlllie the contact 11 while the end 9 of arm 7 W111 pass over said contact and strike the taller contact 12 on further movement of the shaft 6. When shaft 6 rotates in the opposite direction, one or the other of said arms will strike contact 13. Secured ad'acent the outer end of shaft 6 is a normally horizontal vane 14, which is adapted to set itself in the direction of the air .ltS in elevation, which vane constiti. ,refore an angle'of incidence indicator. -he said vane is preferably secured to a sleeve 15 loosely mounted. on shaft 6, but which is normally secured thereto by a spring pressed block 16 which engages a slightly flattened .86 a portion 17 of shaft 6. By this means I. pro vide a safety catch which 'will avoid the breakage of the contacts 7 and 8 in case the vane is accidentally twisted through a large angle. Another means for protecting the contacts.is to rovide a lug 18 secured-' to-shaft 6 and pre erably forming a part of the block 19 to which the contacts are se-- cured. Said lug is adapted to strike stops ing 3. i 7 nor indicating side slip I provide a normally vertical vane 120 which is pivotedon a shaft 21 extendin preferably at ri htangles tofshaft ,6. ounted on said sha is a beveledlgear 22 which meshes with bevel gear 23 on the sleeve 24 surrounding and journaled upon shaft 6. Said sleeve carries contact members 25 and 26 similar to contact arms 7 and 8, andhav'mg their ends 27 and 28 ofi-set ina similar manner. Arm 26 is ada ted to strike contact 29, while upon. further movement of sleeve 2)., arm 25 will strike point 30. Rotation of sleeve 24 in the other direction will-cause arm 25 to no lines 31.

For indicating in connection with the ;climbing angle of the aeroplane, i. e. the

moving in. a line corresponding to its fore angle of incidence, the vane 14 as we have seen is horizontal. 'When the craft is moviii gl forward, the vane streams mi ht out.

en the craft is pointed upwa ly and and aft axis, the vane Wlll stream out along the said line since the movement of the air relative to the craft .is along said line. When, however, the craft is pointing upwardly at too steep an angle, so that the engine is unable to lift it at such a rate as to cause it to move along the line of its fore and aft axis, it will slip forward as it climbs, and its actual course will be alo a line at an angle to the said fore and a axis. The vane 14 will then obviously lie along the linerepresenting the actual upward course of the craft, and will thus be at an angle with the craft. When the fore and aft axis of the craft assumes a predeter mined angle to its actual line of ascent, contact 10 is designed to engage point 11, and light 34 will indicate that the craft is climbmg at its'maximum angle; but when the angle becomes greater and the craft moves forward without rising at all or even moves forward and begins to fall, contact 9 will engage point 12 and light 35 will indicate that the craft is stalling. Similarly, when the craft dives, and more especially at the begin-, ning of the dive, when the craft is suddenly pointed downwardly and its forward momentum carries it ahead of the line represented by its fore and aft axis, if this movement ahead relative to the axis approachesa rate beyond which there would be danger of the craft turning over, contact 10 is adapted to engage point 13 and light 36 will indicate the situation.

Exterior of casing 3 so as to be visible to the pilot are located a air of pointers 51 and 52 which are readab e upon graduations 53 upon casing 3. Pointer 52 is secured to i the aeroplane in a position near the shaft 6 so as to indicate the angle of incidence, while pointer 51 is secured to sleeve 24 indicating, therefore, the side slip.

The contacts above described are placed in circuit with a receiver 33, suitably located1 on ot' for instance, as shown in Fig. 6. Said re ceiving instrument may comprise any suitable e ectrically operated optical device and is shown as com rising a plurality of electric lamps of suitab e characteristics and marktact 11 and-as shown in Fig. 7 preferably dicates when .lighted that the machine is climbing at the maximum permissible angle.

should. This may indicate that the machine is not banked enough upon a turn, and is skidding, or it may indicate that the machine is banked too much, and is slipping toward the center of the turn, or it may indicate a number of other undesirable sltuations causing side slip. If further side slipping occurs in either direction, a red light 49 or 50 will be-lighted indicatin that the amount of side slip has become angerous and must be immediately corrected.

From the above it will be apparent that I 'the machine is side slipping more than it have provided a simple,,reliable and useful indicator for aeroplanes, by which the dot may be kept informed at all times 0 the exact condition of the machine with respect to the air currents, and whereby both preliminary warning and danger signals are shown. In accordance with the provisions of the patent statutes, I have herein described the principle of operation of my invent1on, together with the ap aratus, which I now consider to represent t e best embodiment thereof, but I desire to have it understood that the apparatus shown is only illustrative and that the invention can be carried out by other means. Also, while it is designed to use the various features and elements in the combination and relations described, some of these may be altered and others omitted without interfering with the more generalresults outlined, and the invention extends to such Having described my invention, what I claim and desire to secure by Letters Patent is:

III

III

1. An air current indicator com rising, a

wind operable vaneadapted to p ace itself in the direction of the wind, a contact member connected to said vane and provided with a plurality of arms and a plurality of contacts, each of said contacts being engageableonly bye. corresponding one of said 1 the wind in a plurality of planes, a common mounting for said devices, electrical signaling means controlled by said'devices forpro- Lame? i i a 'ducing a warning when the position of the rection of the wind in a plurality of planes, 10

craft relative to the direction of the wind to a contact member connected to each of said one or both planes attains a predetermined vanes provided with a plurality of arms, a value, and an additional means controlled by plurality of contacts, each of said contacts 5 such devices for producing danger signals being engageable only by acorresponding when said relative position becomes critical. one of said arms, and a distinctive signal op- 15 3. An air current indicator for airplanes erated by the contacts of each vane and arm. comprising a plurality of wind operable In testimon whereof I afiix msi ature. vanes adapted to place themselves in the di-' AWI-ENCE B. S E RY. 

